lix/doc/manual/rl-next/build-dir.md

---
synopsis: "Add a `build-dir` setting to set the backing directory for builds"
cls: 1514
credits: [roberth, tomberek]
category: Improvements
---

`build-dir` can now be set in the Nix configuration to choose the backing directory for the build sandbox.
This can be useful on systems with `/tmp` on tmpfs, or simply to relocate large builds to another disk.

Also, `XDG_RUNTIME_DIR` is no longer considered when selecting the default temporary directory,
as it's not intended to be used for large amounts of data.
Add build-dir setting, clean up default TMPDIR handling This is a squash of upstream PRs #10303, #10312 and #10883. fix: Treat empty TMPDIR as unset Fixes an instance of nix: src/libutil/util.cc:139: nix::Path nix::canonPath(PathView, bool): Assertion `path != ""' failed. ... which I've been getting in one of my shells for some reason. I have yet to find out why TMPDIR was empty, but it's no reason for Nix to break. (cherry picked from commit c3fb2aa1f9d1fa756dac38d3588c836c5a5395dc) fix: Treat empty XDG_RUNTIME_DIR as unset See preceding commit. Not observed in the wild, but is sensible and consistent with TMPDIR behavior. (cherry picked from commit b9e7f5aa2df3f0e223f5c44b8089cbf9b81be691) local-derivation-goal.cc: Reuse defaultTempDir() (cherry picked from commit fd31945742710984de22805ee8d97fbd83c3f8eb) fix: remove usage of XDG_RUNTIME_DIR for TMP (cherry picked from commit 1363f51bcb24ab9948b7b5093490a009947f7453) tests/functional: Add count() (cherry picked from commit 6221770c9de4d28137206bdcd1a67eea12e1e499) Remove uncalled for message (cherry picked from commit b1fe388d33530f0157dcf9f461348b61eda13228) Add build-dir setting (cherry picked from commit 8b16cced18925aa612049d08d5e78eccbf0530e4) Change-Id: Ic7b75ff0b6a3b19e50a4ac8ff2d70f15c683c16a 2024-03-22 21:41:50 +00:00			`---`
			synopsis: "Add a `build-dir` setting to set the backing directory for builds"
			`cls: 1514`
			`credits: [roberth, tomberek]`
			`category: Improvements`
			`---`

			`build-dir` can now be set in the Nix configuration to choose the backing directory for the build sandbox.
			This can be useful on systems with `/tmp` on tmpfs, or simply to relocate large builds to another disk.

			Also, `XDG_RUNTIME_DIR` is no longer considered when selecting the default temporary directory,
			`as it's not intended to be used for large amounts of data.`